feat: PITR RECOVER TO TIMESTAMP, OpenTelemetry OTLP export, FTS infrastructure

- RECOVER TO TIMESTAMP '...' — parser + executor, replays WAL entries
- core/tracing.nim — OTLP/HTTP export via exportOtlp()
- FTS: ftsIndexes table in ExecutionContext, engine import ready
- 281 tests, 0 failures

PLAN.md

@@ -1,49 +1,15 @@
 # BaraDB — Оставащи задачи
 
-> Завършеното е преместено в `PLAN_DONE.md`.
+> Завършеното е в `PLAN_DONE.md`.
 
 ---
 
 ## Ниски (nice-to-have, не блокират production)
 
-### 1. Full FTS index integration (BM25 ranking)
-- **Статус:** ⚠️ Базова поддръжка
-- **Текущо:** `WHERE col @@ 'query'` прави case-insensitive term match. FTS engine (`fts/engine.nim`) съществува с BM25, inverted index, tokenization.
-- **Липсва:** Пълна интеграция — `CREATE INDEX ... USING FTS` автоматично поддържа InvertedIndex при INSERT/UPDATE/DELETE. `@@` използва BM25 вместо substring.
-
-### 2. Point-in-time recovery (PITR)
-- **Статус:** ⚠️ WAL reader добавен
-- **Текущо:** `readEntries(path, untilTimestamp)` чете WAL entries до даден timestamp. Backup/restore чрез tar.gz snapshot работи.
-- **Липсва:** `RECOVER TO TIMESTAMP '...'` команда, която прилага WAL entries до timestamp.
-
-### 3. OpenTelemetry tracing
-- **Статус:** ⚠️ Базов tracer
-- **Текущо:** `core/tracing.nim` — span recording, enable/disable, JSON export. `executeQuery` създава span за всяка заявка.
-- **Липсва:** OTLP/gRPC export, integration с external collector.
-
----
-
-## Завършено в последните 2 сесии (2026-05-07)
-
-### Session 1: SQL Features
-- Recursive CTE (WITH RECURSIVE + UNION ALL)
-- UNION / INTERSECT / EXCEPT
-- DROP INDEX
-- VIEW DDL persistence
-- JSON path operators (`->`, `->>`)
-- FTS SQL wiring (`WHERE col @@ 'query'`)
-- Multi-column index range scans
-- Covering index optimization
-- SCRAM-SHA-256 authentication
-
-### Session 2: Production Hardening
-- JWT secret — `getEffectiveJwtSecret()` helper + warning log при липса на конфигурация
-- SSTable metadata — коментари изяснени (offsets се patch-ват коректно)
-- LSM thread-safety — locks вече съществуват, stress test обновен
-- WAL reader — `readEntries(path, untilTimestamp)` за PITR
-- OpenTelemetry — `core/tracing.nim` с span recording, `executeQuery` tracing
-- Distributed 2PC — реален TCP RPC вместо simulated (host="" → local fallback)
-- `addParticipant` има default параметри (host="", port=0)
+### 1. Full FTS BM25 ranking in `@@`
+- **Статус:** ⚠️ Инфраструктура готова
+- **Текущо:** `ftsIndexes: Table[string, InvertedIndex]` в ExecutionContext. FTS engine (`fts/engine.nim`) с BM25, tokenization. `@@` прави term-based substring match.
+- **Липсва:** `evalExpr` няма достъп до `ctx` за BM25 lookup. Трябва refactoring на evalExpr signature или FTS filter на ниво `executePlan`.
 
 ---
 
@@ -56,4 +22,18 @@
 
 ---
 
-**279 теста — 0 failure-а.**
+## Завършено (обща сума: 3 сесии)
+
+**281 теста — 0 failure-а.**
+
+### Session 1: SQL Features
+- Recursive CTE, UNION/INTERSECT/EXCEPT, DROP INDEX, VIEW persistence
+- JSON path (`->`, `->>`), FTS SQL (`@@`), multi-col range scan, covering index, SCRAM auth
+
+### Session 2: Production Hardening
+- JWT security, WAL reader, tracing spans, 2PC real RPC, stress test fix
+
+### Session 3: PITR + OpenTelemetry
+- `RECOVER TO TIMESTAMP` — parser + executor (WAL replay)
+- `core/tracing.nim` — OTLP/HTTP export (`exportOtlp`)
+- FTS infrastructure — `ftsIndexes` in ExecutionContext, engine import